Wing fold actuator system for aircraft

Abstract

An improved actuator system is provided for safe displacement of a folding wing section of an aircraft between a folded storage position and a deployed position for normal flight operations. The actuator system comprises an electrohydraulic actuator forming part of a mechanical linkage between an outboard folding wing section and an adjacent inboard wing section. The electrohydraulic actuator is adapted to be reversibly driven either electrically or hydraulically to displace the outboard wing section, and includes an improved brake unit for automatically retaining the outboard wing section in place upon interruption of drive power input to the actuator. The actuator system further includes an improved latch pin unit adapted for electric or hydraulic powered operation to positively lock the outboard wing section in the deployed position.

What is claimed is: 
     
       1. A wing fold actuator system for use in an aircraft having an outboard wing section connected to an inboard wing section for movement between a deployed position and a folded position said actuator system comprising: an electrohydraulic actuator connected between the inboard and outboard wing sections, said electrohydraulic actuator including a driven member for displacing the outboard wing section between the deployed and folded positions;   said electrohydraulic actuator includes a power cylinder having a base end connected to one of the inboard and outboard wing sections, and a ram adapted for extension and retraction movement with respect to said power cylinder and having a free end connected to the other at the inboard and outboard wing sections;   said electrohydraulic actuator further including hydraulic drive means and electric motor drive means alternatively operable for reversible power drive displacement of said driven member, said electric motor drive means including a rotatable output shaft connected to said driven member, said output shaft being rotatably back-driven by said driven member upon operation of said hydraulic drive means to displace said driven member; and said hydraulic drive means includes a power piston connected to said ram and mounted within power cylinder, said power piston cooperating with said power cylinder to define a pair of fluid chambers at opposite sides of said power piston, and means for controllably supplying hydraulic fluid under pressure to one of said chambers while exhausting the other of said chambers to displace said power piston within said power cylinder;   said actuator further includes a central drive shaft, and reversible transmission means for rotating said drive shaft in response to displacement of said power piston within said power cylinder, said output shaft of said electric motor drive means being connected to said drive shaft for rotation therewith; and   a brake unit for preventing displacement of said driven member upon interruption of power drive displacement thereof, said brake unit including a brake member carried on said output shaft for rotation therewith, a friction member, means for engaging said brake and friction members to prevent rotation of said output shaft in the absence of operation of one of said drive means, and means for disengaging said brake and friction members to permit rotation of said output shaft during operation of one of said drive means for power drive displacement of said drive member.   
     
     
       2. The wing fold actuator system of claim 1 wherein said transmission means comprises a ball nut and screw assembly. 
     
     
       3. The wing fold actuator system of claim 1 wherein said electric motor drive means comprises a reduction gear train connected between said drive shaft and said output shaft. 
     
     
       4. The wing fold actuator system of claim 1 wherein said brake member comprises a brake disk. 
     
     
       5. The wing fold actuator system of claim 1 wherein said means for engaging said brake and friction members comprises a nonrotational arbor having said friction member mounted thereon and adapted for movement between a first position with said brake and friction members engaged and a second position with said brake and friction members disengaged, and spring means for biasing said arbor toward said first position. 
     
     
       6. The wing fold actuator system of claim 5 wherein said means for disengaging said brake and friction means comprises a brake piston connected to said arbor and means for applying hydraulic fluid under pressure to said brake piston during operation of said hydraulic drive means to displace said arbor to said second position, and electromagnetic means for displacing said arbor to said second position during operation of said electric motor drive means. 
     
     
       7. A wing fold actuator system for use in an aircraft having an outboard wing section with a latch pin unit for releasably locking the outboard wing section to an inboard wing section said actuator system comprising: an electrohydraulic actuator connected between the inboard and outboard wing sections, said electrohydraulic actuator including a driven member for displacing the outboard wing section between the deployed and folded positions;   said electrohydraulic actuator further including hydraulic drive means and electric motor drive means alternatively operable for reversible power drive displacement of said driven member, said electric motor drive means including a rotatable output shaft connected to said driven member, said output shaft being rotatable back-driven by said driven member upon operation of said hydraulic drive means to displace said driven member;   a brake unit for preventing displacement of said driven member upon interruption of power drive displacement thereof, said brake unit including a brake member carried on said output shaft for rotation therewith, a friction member, means for engaging said brake and friction members to prevent rotation of said output shaft in the absence of operation of one of said drive members, and means for disengaging said brake and friction members to permit rotation of said output shaft during operation of one of said drive members for power drive displacement of said drive member; and   wherein said latch pin unit includes an extensible latch pin, and further including electrohydraulic means for displacing said latch pin between extended and retracted positions.   
     
     
       8. A wing fold actuator system for use in an aircraft having an outboard wing section with a latch pin unit for releasably locking the outboard wing section to an inboard wing section said actuator system comprising: an electrohydraulic actuator connected between the inboard and outboard wing sections, said electrohydraulic actuator including a driven member for displacing the outboard wing section between the deployed and folded positions;   said electrohydraulic actuator further including hydraulic drive means and electric motor drive means alternatively operable for reversible power drive displacement of said driven member, said electric motor drive means including a rotatable output shaft connected to said driven member, said output shaft being rotatable back-driven by said driven member upon operation of said hydraulic drive means to displace said driven member;   a brake unit for preventing displacement of said driven member upon interruption of power drive displacement thereof, said brake unit including a brake member carried on said output shaft for rotation therewith, a friction member, means for engaging said brake and friction members to prevent rotation of said output shaft in the absence of operation of one of said drive members, and means for disengaging said brake and friction members to permit rotation of said output shaft during operation of one of said drive members for power drive displacement of said drive member; and   wherein said latch pin unit includes a latch pin movable along a longitudinal axis of said pin between extended and retracted positions, and means for rotating said latch pin about said axis during movement between said extended and retracted positions.   
     
     
       9. A wing fold actuator system for use in an aircraft having an outboard wing section connected to an inboard wing section for folding movement between a deployed position and a folded position, said actuator system comprising: an hydraulic power cylinder connected to one of the inboard and outboard wing sections;   a power piston mounted within said power cylinder;   a ram carried by said power piston and projecting from said power cylinder and being connected to the other of said inboard and outboard wing sections;   an electric drive motor having a rotatable output shaft;   transmission means connected between said power piston and said output shaft for reversibly driving said output shaft in response to translation of said power piston within said power cylinder;   a brake member carried on said output shaft for rotation therewith;   a nonrotational friction member;   spring means for normally displacing said friction member into braking engagement with said brake member to normally prevent rotation of said output shaft and thereby also prevent translation of said power piston within said power cylinder;   hydraulic drive means for supplying hydraulic fluid under pressure to said power cylinder for translating said power piston therein, said hydraulic drive means including hydraulic brake release means for displacing said friction member out of braking engagement with said brake member during supply of the hydraulic fluid under pressure to said power cylinder, thereby permitting rotation of said output shaft; and   electric drive means for driving said electric motor to rotatably drive said output shaft and thereby translate said power piston within said power cylinder, said electric drive means including electric brake release means for displacing said friction member out of braking engagement with said brake member during driving operation of said electric motor thereby permitting rotation of said output shaft;   said hydraulic and electric brake release means permitting spring-loaded re-engagement of said brake and friction members upon respective operational interruption of said hydraulic and electric drive means.   
     
     
       10. The wing fold actuator system of claim 9 wherein said transmission means comprises a ball nut and screw assembly. 
     
     
       11. The wing fold actuator system of claim 10 wherein said transmission means further includes a reduction gear train. 
     
     
       12. The wing fold actuator system of claim 9 further including at least one latch pin unit for releasibly locking the outboard wing member in the deployed position. 
     
     
       13. The wing fold actuator system of claim 12 wherein said latch pin unit includes a latch pin movable between extended and retracted positions, said latch pin including means for expanding the cross sectional size of said latch pin upon movement thereof to said extended position. 
     
     
       14. The wing fold actuator system of claim 12 wherein said latch pin unit includes a latch pin movable along a longitudinal axis of said pin between extended and retracted positions, and means for rotating said latch pin about said axis during movement between said extended and retracted positions.